Method of winding coils

ABSTRACT

A method for winding coils for the stator of an electric motor uses apparatus which includes a support arrangement onto which the coils are wound, which comprises a plurality of elongate supports either in the form of rods or shaped support elements, the supports are arranged in coaxial groups in such a way that the ends of the supports of each group lie in a plane which is at an angle to the axis of the supports. The method includes the steps of winding a coil on a selected group of first and second supports by rotation of the winding head and then advancing the winding head along its axis of rotation to wind subsequent coils on further groups of supports. The axis of rotation of the winding head lies at an angle to the axis of the support arrangement such that coils are initially wound at an angle to the supports but progressively slide to adopt a plane perpendicular to the axis of the supports by virtue of the tension on the wire as it is being wound.

.SHEU 2 of s 8 86. Ba Ba (980 I .FIG- 2 b 10c 10d PATENTEmummr Y 3'817'295 sumuurs v METHOD OF WINDING COILS BACKGROUND OF THE INVENTION The present invention relates to a method of winding coils, and particularly to the winding of coils of insulated metal wire for the stators of electric motors.

Generally, coils of this type are formed by winding the wire over suitable formers, after which the coil thus produced is inserted into the stator either manually or by machine; in the lattercase the coils must be conveniently arranged in layers in such a manner that the thickness of the layers is less than that of the spaces between the rods of the inserting device.

Stratification of the coils into layers is normally obtained during winding on the formers; in general fixed formers are preferred upon which the coils are formed by a winding device, since such a system allows a relatively rapid transfer of the coils on to the insertion equipment. For this purpose various types of formers are used, these may be constituted by a single body or by a plurality of peripheral rods which correspond to the shape of the winding former; these are provided with control mechanisms in order to slacken the coils, or a device capable of taking the coils from the former itself to transfer them to the inserting equipment.

In order to separate the coils on the former into one or more layers it is possible to move the winding device by a predetermined pitch as the winding proceeds, or alternatively the device may remain fixed and the turns which are formed on the coils may be moved axially by means of a device, which advances the turns themselves with respect to the former.

In each case the former and the auxiliary equipment used are complex and expensive to manufacture, difficult to operate and susceptible to damage.

An improvement in winding operations can be obtained by a system described in Italian Patent 852,287 which utilises a stepped former the longitudinal profile of which is calculated so that the successive turns of a coil slip naturally from it to pass either on to a loading device having a plurality of segments, capable of receiving a whole layer of coils of a multipolar stator, or directly on to the inserting device of an automatic machine; in thefirst case, once the loadingdevice has been used, it can be extracted from the machine, and may be used subsequently for manual or automatic transfer of the remaining coils on to the inserting device.

This system does have certain disadvantages however, for example, the use of a former with one or more steps, necessarily comprising joined surfaces, which is separate from the support device, is expensive as the work has to be done with extreme accuracy, and in addition, sometimes not all the spirals of a coil slide over onto the support device, this problem arises particularly with the last turns of a coil, but sometimes effects all the turns if they are few in number. In order to overcome this problem it is necessary to equip the former with an ejector device and associated controls, which operate to push any turns which fail to slip from the former on to the support device. The ejector device must be also capable of pushing the entire coil, when completed on a support device, to one end thereof and also to secure the turns of one pole from slipping to the successive one. Moreover, at the commencement of winding each subsequent pole, the initial winding tension causes a shortening of the last turns of the last coil of the immediately preceding pole, and therefore it is necessary to provide automatic intermediate locking of the wire thereby requiring the addition of a suitable arrangement which also requires operating time; alternatively it would be possible to arrange to maintain the coils on the support device in tension, by adding a supplementary plate provided with tension supports for the various coils for each pole.

Another disadvantage of this prior system is that the presence of the stepped former and the ejector device in the centre of the winding mandrel makes it necessary for the upstanding winding guides to be rather long and this presents a limitation on the winding speed. With this device it is only possible, with concentric coils to wind from the smallest coil to the largest so that the connection from one pole to the next in series must be made always from the largest coil of one pole to the smallest coil of the next pole, and for this reason the connection wires are excessively long.

The eccentricity between the stepped former and the axis of rotation of the winding mandrel makes it difficult, or impossible, to wind very-long coils, in fact coils having a length of mm require an aperture between the winding bows of at least 250 mm. Finally, when winding with this apparatus, it is necessary to disengage the former and to advance it each time it is desired to proceed from winding one pole to winding the next, and this entails a loss of production time which is greater the greater the number of poles of the winding.

OBJECTS OF THE INVENTION One object of the present invention is to provide a method of winding coils in which the disadvantages set out above are reduced or eliminated, but which retains the advantages of simplicity and universality of the natural stratification system.

Another object of the present invention is to dispense with the former thus obtaining various economic and technical advantages.

A further object of the invention is to provide a winding procedure in which dead times are reduced, therebynotably increasing production even when utilising only the same winding speed as has been used hithertofore.

Yet another object of this invention is to reduce the length of the connection wires between one pole and the next, and to adopt smaller rotation radii of the winding head.

Yet a further object of the invention is to provide a winding procedure which allows a substantial simplification of the equipment necessary for its performance.

SUMMARY OF THE INVENTION According to one aspect of the present invention a method of winding coils for the stator of an electric motor comprises the steps of providing a winding guide carried by a rotatable winding head, providing adjacent the winding head a support arrangement comprising at least one array of parallel elongate first supports projecting from a baseplate, each support being of a different length from the adjacent support, and providing at least one array of elongate second supports parallel to the said array of first supports, each second support being of different length from the adjacent second support, the two arrays being arranged so that the first supports and the second supports form a plurality of coaxial groups the ends of each group of supports lying in the same plane and delimiting the shape of a former for respective coils, the axis of the support arrangement forming an angle with the axis of rotation of the winding head which is greater than the angle of friction between the wire and the supports, winding the turns of the coil on a selected group of supports by rotation of the winding head about the said axis thereof, in such a manner that each turn is initially formed in a plane perpendicular to the axis of rotation of the winding head defined by the ends of the group of supports, but is urged to slide along the first supports of the group by a component of the tension on the wire due to the inclination between the axis of the support arrangement and the axis of the winding head thereby assuming a position lying in a plane substantially perpendicular to the axis of the supports of the support arrangement.

The present invention also comprehends a support arrangement for a coil winding machine having a winding head rotatable about a first axis, the support arrangement comprising at least one array of parallel elongate first supports projecting from a mounting plate, and at least one array of elongate second supports, the two arrays of supports forming a plurality of coaxial groups of supports, the supports of any one group having such a length that the ends of the group lie in a plane which, when the support arrangement is in an operative position with respect to the winding head lies substantially perpendicular to the axis of rotation thereof.

Various other features and advantages of the invention will become apparent during the course of the following description with reference to the accompanying drawings which is given purely by way of nonrestrictive example.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic side elevation view of one embodiment of the invention on which a method of winding coils according to the present invention can be performed;

FIG. 2 is a diagrammatic plan view of the embodiment of FIG. 1;

FIG. 3 is a diagrammatic plan view of a second embodiment of the invention;

FIG. 4 is a partial transverse section, on an enlarged scale, taken on the line IV-IV of FIG. 3;

FIG. 5 is a partial diagrammatic plan view of a third embodiment of the invention;

FIG. 6 is a diagrammatic side view of a fourth embodiment of the invention;

FIG. 7 is a partial diagrammatic plan view of the embodiment of FIG. 6;

FIG. 8 is a diagrammatic side view of another embodiment of the invention; and

FIG. 9 is a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With referencenow to FIGS. 1 and 2, there is shown an insulated metal wire 1 which is to be used for the formation of a coil on a support device 6 by a rotating winding head having a pulley 2 carried by a winding guide 3, upstanding from a rotating plate 4; the winding head rotates about a horizontal axis X X. Opposite the head there is arranged a support device generally indicated 6, which comprises a plate 14 rotatable about a central axis Y Y, which forms an angle a with the axis X X of rotation of the mandrel, which is greater than the angle of friction between the turns of the wire 1 and the metal bodies with which the wire comes into contact.

On the plate 14 there is mounted a first series of parallel supports in the form of rods 8 which in the embodiment illustrated in FIG. 1 form part of a support device 6 comprising a circular plate 7 and two arrays of supports 8, 9. Each rod of the two arrays is of different length from the adjacent supports and the supports are arranged in coaxial groups in such manner that the straight line joining the ends of the supports of any one group lie in a plane orthogonal to the axis of winding X X. The array of supports 9 may be formed as a series of rods 9 or as a series of segments 21a, 21b, 21c, as shown in the embodiment of FIG. 5, shaped as the profiles of the coils and positioned so as to guide the wire in the corresponding channels between the rods 8, which are of greater length.

The rods 8 could also be replaced by any other suitable supports for receiving the successive coils of each pole in order to transport them to the inserting equipment in the correct relative positions.

Peripherally about the plate 14 there are located a number of further plates 12, each of which carries an array of second supports in the form of rods or studs 10 which assist in defining the various coils; the number of plates 12 is the same as the number of the poles of the stator. The rods or studs 10 have lateral projections 11 at the ends thereof which are shaped with a curved surface smoothly joining the surface of the rod. The straight line joining the free ends of the studs 10 is contained in a vertical plane. The heads of the rods 10 could be replaced by a profiled stepped form fixed to the winding mandrel, although such an arrangement is generally less satisfactory than the one described because it complicates the equipment.

The studs or rods 10 may be replaced by laminations of suitable form, such as the laminations 19a, 19b shown in FIGS. 3 and 4 having a sloping or curved profile. Each plate 12 carrying the rods 10 of the peripheral array thereof is pivotally mounted on a transverse shaft 13 and is held in position by a spring biased stud l6 and a rigid stud 17 which is adapted to co-operate with a profiled cam 18. This allows for slackening of the coils wound on the rods 10 to allow extraction of the support device when the coils have been positioned on a stator.

Guiding pins 20a, 20b, may be set in a position suitable for determining the correct shape of the various coils S1, S2, S3 The support device 6 may be formed as an inserting device 22 of an automatic machine 22, as shown in FIGS. 6 and 7; in a case such as this it is preferable to use profiled laminations 21 as the supports for guiding the coils, these are arranged between the parallel rods 23 which themselves are formed with an asymmetric cross section.

FIG. 8 illustrates a coil winding machine for winding a complete series of poles by the method of the present invention. This machine comprises a base 25 supporting a winding head 26 which is adjustable in height, and a divider 29 with a vertical axis (Z Z) carrying two sets of support devices 5, 5' rotatable about an inclined axis Y Y. The winding head 26 comprises a winding mandrel 27 rotatable in a sleeve 28 which is axially movable in increments at any selected pitch. Control of the rotation of the mandrel is achieved either by means of electrical control or, alternatively, by hydraulic control, which is arranged to stop the rotation after a predetermined number of turns, and is manually adjustable to effect slowing or stopping of the rotation should this be necessary.

Control of the incremental advance may be effected by any mechanical, pneumatic or hydraulic control arrangement by means of which the successive steps are fixed. The axis X X 'of rotation of the mandrel is arranged horizontally and forms an angle a with the axis Y Y of the equipment 5, 5.

The divider 29 which rotates about the vertical axis Z Z is positioned so that each receiving apparatus 5 or 5' is alternately moved to a position adjacent the winding head. Each support device is of the type described above and the particular configuration determines the type of stator or winding to be formed.

The general arrangement of the machine described may be changed by having a different number of winding heads, or a different number of support devices.

Another possible arrangement of the machine is illustrated in FIG. 9, in which the support device is replaced by the inserting equipment 22 and 22', carried on a plate 30 which is rotatable about an inclined axis Z Z which forms an angle a with the axis X X of rotation of the winding head 26. In this embodiment the axis X X lies at a small angle to the vertical.

The winding operation effected by machine as described above can be effected as follows; the end of the wire to be wound is held by any automatic or manual system. As shown in FIG. I, initially the winding head 4 which carries the guide 3, advances along the axis X X until the wire delivered from the pulley 2 is located in a plane Al which is orthogonal to the axis of rotation 'X X, after which the winding head begins to rotate about the axis X X until it completes a predetermined number of revolutions.

During this operation the successive turns of wire wound in the plane Al will slide naturally along the rods 8 on which they are wound until they lie in the plane A normal to the axis of the rods 8 of the support device 6, engaging the rods 8a thereof and the auxiliary rods a which project from the plate 12. Thus the first coil S1 is formed with substantially parallel turns as the tension of each successive turn will draw the preceding turn to move parallel to the plane A due to the inclination between the axis of the equipment and the winding axis.

When the turns are first wound they have a certain length, and this becomes less and less as they near the plane A, by the effect of the tension exerted on the wire by the winding head. When the predetermined number of turns have been wound, the winding head 4 automatically advances along the axis X X so as to wind the wire next in a plane A2 thus forming a second coil S2 of the pole. In this case the rods 8bof the device 6 are used as the former, together with the auxiliary stud 10b of the plate 12. The same operations are repeated for the planes A3, A4 and so on until all the coils of one pole have been. wound upon the support device 6.

When all the coils of the pole have been wound the winding head 4 is stopped in a predetermined position and the support device is rotated about the axis Y Y by an angle corresponding to the angle of the required phase difference between the poles. The winding head then recommences to turn, but this time in the opposite direction of rotation to that of the preceding pole, and a fresh winding cycle is commenced, beginning at the winding plane A4 of the last formed coil. In the same manner the process will continue for all the subsequent poles connected in series so as to form a complete set of poles. If the winding is effected upon a machine of the type illustrated in FIG. 8, when one set of poles is completed, the divider 29 will rotate about its vertical axis Z Z to bring a second support device 5' into alignment with the winding head 4 to be wound as described above and the support device 5 which carries the coils wound up to this point is removed so as to transfer the coils on to inserting equipment (not shown).

It will be appreciated that when the coils are wound directly onto the inserting device 22, as in the case of the machine shown in FIG. 9, it is only necessary to load the partly formed stator onto the inserting device and to proceed to the insertion of the coils.

We claim:

ll. A method of winding coils of wire for the stator of an electric motor, comprising steps of:

providing a winding guide carried by a winding head which is rotatable about a first axis,

providing adjacent said winding head a support arrangement comprising a support arrangement for a coil winding machine of the type having a winding head rotatable about a first axis, said support arrangement comprising a mounting plate at least one array of substantially parallel elongate first supports projecting from said mounting plate,

at least one array of substantially parallel elongate second supports, the two arrays of supports forming a plurality of coaxial groups of supports the supports of any one group of which are each of such a length that the ends thereof delimit the shape of a former of a respective coil and lie in a plane which, when said support arrangement is in an operative position with respect to said winding head, lies substantially perpendicular to said first axis of rotation, the axis of said support arrangement forming an angle with respect to said first axis which is greater than the angle of friction between said wire and said first and second supports,

winding the turns of the coil on a selected group of said first and second supports by rotation of said winding head about said first axis such that each turn is initially formed in a plane perpendicular to said first axis defined by the ends of said selected group of first and second supports, but is urged to slide along said first supports of said group by a component of the tension in the wire due to the inclination between said first axis and said axis of said support arrangement, thereby assuming a position lying in a plane perpendicular to said axis of said support arrangement.

2. The method of claim ll further comprising the steps of:

moving said winding head a selected distance along said first axis after a predetermined number of turns of said coil have been wound on said selected group of first and second supports,

each time a coil is completed until all the coils of 7 one pole have been wound, whereupon said support arrangement is moved out of alignment with said winding head. 

1. A method of winding coils of wire for the stator of an electric motor, comprising steps of: providing a winding guide carried by a winding head which is rotatable about a first axis, providing adjacent said winding head a support arrangement comprising a support arrangement for a coil winding machine of the type having a winding head rotatable about a first axis, said support arrangement comprising a mounting plate at least one array of substantially parallel elongate first supports projecting from said mounting plate, at least one array of substantially parallel elongate second supports, the two arrays of supports forming a plurality of coaxial groups of supports the supports of any one group of which are each of such a length that the ends thereof delimit the shape of a former of a respective coil and lie in a plane which, when said support arrangement is in an operative position with respect to said winding head, lies substantially perpendicular to said first axis of rotation, the axis of said support arrangement forming an angle with respect to said first axis which is greater than the angle of friction between said wire and said first and second supports, winding the turns of the coil on a selected group of said first and second supports by rotation of said winding head about said first axis such that each turn is initially formed in a plane perpendicular to said first axis defined by the ends of said selected group of first and second supports, but is urged to slide along said first supports of said group by a component of the tension in the wire due to the inclination between said first axis and said axis of said support arrangement, thereby assuming a position lying in a plane perpendicular to said axis of said support arrangement.
 2. The method of claim 1 further comprising the steps of: moving said winding head a selected distance along said first axis after a predetermined number of turns of said coil have been wound on said selected group of first and second supports, rotating said winding head to form a second coil on a second selected group of first and second supports the ends of which lie in a second plane substantially perpendicular to said first axis, and subsequently moving said winding head a predetermined distance in the direction of said first axis each time a coil is completed until all the coils of one pole have been wound, whereupon said support arrangement is moved out of alignment with said winding head. 